Project description:full title: A mitochondrial long-chain fatty acid oxidation defect in a mouse model leads to dysregulation of plasma long-chain acylcarnitines, dysregulation of plasma amino acids, and an increased reliance on glucocorticoid signaling to maintain euglycemia during fasting. [liver] The liver is a major source of energy substrates during metabolic stress: fasting, prolonged exercise, febrile illness. Fasting-induced hypoglycemia is a characteristic feature of FAO disorders including very long chain acyl-CoA dehydrogenase (VLCAD) deficiency (VLCADD). However, the pathophysiological mechanisms that underlie the diversity of clinical presentation of FAO dysfunction are not known. Here, we investigated the transcriptional response in liver tissue to the FAO defect in a model of VLCADD: the long-chain acyl-CoA dehydrogenase (LCAD) knockout (KO) mouse. We found that differentially expressed genes from the liver were associated with molecular networks annotated for fatty acid oxidation and cholesterol biosynthesis from population-based networks.
Project description:ETFDH (electron transfer flavoprotein ubiquinone oxidoreductase) is a 64 kDa protein monomer located in the inner mitochondrial membrane, in charge of transferring the electrons received from the electron transfer flavoprotein ETF to the Coenzyme Q (Q). Pathological mutations in ETFDH lead to Multiple Acyl-CoA Dehydrogenase Deficiency (MADD; OMIM #231680). C2C12 cells lacking ETFDH were analysed by TMT analysis and compared to wt cells.
Project description:A mitochondrial long-chain fatty acid oxidation defect leads to dysregulation of plasma long-chain acyl carnitines, dysregulation of plasma amino acids, and an increased reliance on glucocorticoid signaling to maintain euglycemia during fasting. [muscle] Skeletal muscle tissue relies on products of fatty acid oxidation (FAO) during conditions of metabolic stress: fasting, prolonged exercise, febrile illness. Fasting-induced hypoglycemia and rhabdomyolysis are characteristic features of FAO disorders including very long chain acyl-CoA dehydrogenase (VLCAD) deficiency (VLCADD). However, the pathophysiological mechanisms that underlie the connection between FAO dysfunction and skeletal muscle dysfunction are not known. Here, we investigated the transcriptional response in skeletal muscle tissue (gastrocnemius) to the FAO defect in a model of VLCADD: the long-chain acyl-CoA dehydrogenase (LCAD) knockout (KO) mouse. We found that differentially expressed genes in the muscle were associated with molecular networks annotated for the cellular response to starvation from population-based models. To validate the association between the starvation response and FAO, we pharmacologically inhibited both glucocorticoid signaling and FAO in a model of fasting and observed that mice depleted in both pathways lost less weight during fasting and became hypoglycemic. These findings implicate glucocorticoid signaling as a candidate modifier of the cellular response to starvation in muscle tissue in the context of FAO disorders including VLCADD.
Project description:The mechanisms underlying the formation of acyl protein modifications remain poorly understood. By investigating the reactivity of endogenous acyl-CoA metabolites, we found a class of acyl-CoAs that undergoes intramolecular catalysis to form reactive intermediates which non-enzymatically modify proteins. Based on this mechanism, we predicted, validated, and characterized the protein modification: 3-hydroxy-3-methylglutaryl(HMG)-lysine. In a model of altered HMG-CoA metabolism, we found evidence of two additional protein modifications: 3-methylglutaconyl(MGc)-lysine and 3-methylglutaryl(MG)-lysine. Using quantitative proteomics, we compared the ‘acylomes’ of two reactive acyl-CoA species, namely HMG-CoA and glutaryl-CoA, which are generated in different pathways. We found proteins that are uniquely modified by each reactive metabolite, as well as common proteins and pathways. We identified the tricarboxylic acid cycle as a pathway commonly regulated by acylation, and validated malate dehydrogenase as a key target. These data identify a fundamental relationship between reactive acyl-CoA species and proteins, and define a new regulatory paradigm in metabolism.
Project description:Floodings already have a nearly 60% share in the worldwide damage to crops provoked by natural disasters. Climate change will cause plants to be even more frequently exposed to oxygen limiting conditions (hypoxia) in the near future due to heavy precipitation and concomitant waterlogging or flooding events in large areas of the world. Although the homeostatic regulation of adaptive responses to low oxygen stress in plants is well described, it remained unknown by which initial trigger the molecular response to low-oxygen stress is activated. Here, we show that a hypoxia-induced decline of the ATP level of the cell reduces LONG-CHAIN ACYL-COA SYNTHETASE (LACS) activity, which leads to a shift in the composition of the acyl-CoA pool. High oleoyl-CoA levels release the transcription factor RELATED TO APETALA 2.12 (RAP2.12) from its interaction partner ACYL-COA BINDING PROTEIN (ACBP) at the plasma membrane to induce low oxygen-specific gene expression. We show that different acyl-CoAs provoke unique molecular responses revealing a novel role as cellular signalling component also in plants. In terms of hypoxia signalling, dynamic acyl-CoA levels integrate the cellular energy status into the oxygen signalling cascade with ACBP and RAP2.12 being the central hub. The conserved nature of the ACBP:RAP2.12 module in crops and the novel mechanistic understanding of how low-oxygen stress responses are initiated by oleoyl-CoA in plants provide useful leads for enhancing future food security.
Project description:Transcriptome studies confirm the nitrogen limited physiological state of both the wild-type and mutant cells. In addition, multiple differentially expressed genes involved in the synthesis and consumption of pools of acetyl-CoA, acetoacetyl-CoA and 3-hydroxybutyryl-CoA, key metabolites for PHA and TAG synthesis, were identified. An enrichment analysis of differentially expressed genes in the nitrogen starved wild-type versus the isogenic RHA1_ro02104 mutant strain identified genes in the mutant involved in fatty acid and lipid as well as genes involved in acyl-CoA hydrolysis and triacylglycerol degradation. An 8 x 15K array study using total RNA recovered from triplicate cultures of Rhodococcus jostii RHA1 under nitrogen rich and nitrogen starved conditions and triplicate cultures of Rhodococcus jostii RHA1 TadA-homolog deletion mutants (2104) under nitrogen rich and nitrogen starved conditions.
Project description:Very long-chain acyl-CoA dehydrogenase (VLCAD) is an inner mitochondrial membrane enzyme that catalyzes the first and rate-limiting step of long-chain fatty acid oxidation. Point mutations in human VLCAD can produce an inborn error of metabolism called VLCAD deficiency that can lead to severe pathophysiologic consequences, including cardiomyopathy, hypoglycemia, and rhabdomyolysis. Discrete mutations in a structurally uncharacterized C-terminal domain region of VLCAD cause enzymatic deficiency by an incompletely defined mechanism. Here, we conducted a structure-function analysis, incorporating X-ray crystallography, hydrogen-deuterium exchange mass spectrometry, and computational modeling, to identify a specific membrane interaction defect of full-length, human VLCAD bearing the clinically-observed mutations, A450P or L462P. By disrupting a predicted a-helical hairpin, these mutations either partially or completely impair direct interaction with the membrane itself. Thus, we find that enzyme mislocalization underlies the metabolic deficiency syndrome of patients bearing specific mutations that disrupt the structure of an a-helical membrane binding region of VLCAD.
Project description:Transcriptome studies confirm the nitrogen limited physiological state of both the wild-type and mutant cells. In addition, multiple differentially expressed genes involved in the synthesis and consumption of pools of acetyl-CoA, acetoacetyl-CoA and 3-hydroxybutyryl-CoA, key metabolites for PHA and TAG synthesis, were identified. An enrichment analysis of differentially expressed genes in the nitrogen starved wild-type versus the isogenic RHA1_ro02104 mutant strain identified genes in the mutant involved in fatty acid and lipid as well as genes involved in acyl-CoA hydrolysis and triacylglycerol degradation.
Project description:RNAseq analysis was conducted to complement the targeted and untargeted metabolomics analysis of livers overexpressing the CoA-degrading enzyme Nudt7 or GFP (control). Lipid metabolism requires coenzyme A (CoA), which is found in multiple subcellular compartments including the peroxisomes. In the liver, CoA levels are dynamically adjusted between the fed and fasted states. The elevation in CoA levels that occurs during fasting is driven by increased synthesis but also correlates with decreased expression of Nudt7, the major CoA-degrading enzyme in the liver. Nudt7 resides in the peroxisomes and we overexpressed this enzyme in mouse livers to determine its effect on the size and composition of the hepatic CoA pool in the fed and fasted states. Nudt7 overexpression did not change total CoA levels but decreased the concentration of short-chain acyl-CoAs and choloyl-CoA in fasted livers, when endogenous Nudt7 activity was lowest. The effect on these acyl-CoAs correlated with a significant decrease in the hepatic bile acid content and in the rate of peroxisomal fatty acid oxidation, as estimated by targeted and untargeted metabolomics, combined with the measurement of fatty acid oxidation in intact hepatocytes. Identification of the CoA species and metabolic pathways affected the overexpression on Nudt7 in vivo supports the conclusion that the nutritionally-driven modulation of Nudt7 activity could contribute to the regulation of the peroxisomal CoA pool and peroxisomal lipid metabolism.
Project description:Diagnosis of a patient with Sifrim-Hitz-Weiss syndrome, development and epileptic encephalopathy-14, and medium chain Acyl-CoA dehydrogenase deficiency: a case report